These are typically mainstream commercial relational databases with
“ANSI standard” transaction behavior. If
AutoCommit is off, then changes to the database
won’t have any lasting effect unless commit
is called (but see also disconnect). If
rollback is called, then any changes since the
last commit are undone.
If AutoCommit is on, then the effect is the same
as if the DBI called commit automatically after
every successful database operation. In other words, calling
commit or rollback explicitly
while AutoCommit is on would be ineffective
because the changes would have already been commited.
Changing AutoCommit from off to on should issue a
commit in most drivers.
Changing AutoCommit from on to off should have no
immediate effect.
For databases that don’t support a specific autocommit mode,
the driver has to commit each statement automatically using an
explicit COMMIT after it completes successfully
(and roll it back using an explicit rollback if it
fails). The error information reported to the application will
correspond to the statement that was executed, unless it succeeded
and the commit or rollback
failed.